\subsubsection{Key Management}
\label{sec:721KeyManagement}
There are several pairs of public and private keys to keep track of throughout these protocols. We provide a summary here (for an actor Alice ($A$)):

\begin{center}
	\resizebox{\textwidth}{!}{
	\begin{tabular}{ c c c c c }
		\textbf{Ownership of...} & \textbf{Account symbol} & \textbf{Private Key} & \textbf{Public Key} & \textbf{Notes}\\
		\\
    \makecell{Ethereum address} & $E_A$ & $sk^E_A$ & $pk^E_A$ & Used for `mint' and `burn'. \\
		\\
    \makecell{Anonymous Ethereum addresses} & $\Xi_{A,i}$ & $sk^{\Xi}_{A,i}$ & $pk^{\Xi}_{A,i}$ & Used for `transfer'. $i\in\mathbb{N}$.\\
		\\
    \makecell{Ethereum Whisper accounts} & $W_{A,j}$ & $sk^{W}_{A,j}$ & $pk^{W}_{A,j}$ & Used for private messaging. $j\in\mathbb{N}$\\
		\\
    \makecell{ERC-721 commitment $Z_l$} & $Z_l$ & $sk^{Z,l}_{A}$ & $pk^{Z,l}_{A}$ & Used to `mint', `transfer' and `burn' $Z_l$.\\

	\end{tabular}
	}
\end{center}
\ \\
Hereafter, when we write $sk_A$ and $pk_A$ we will be referring to $sk^{Z,l}_{A}$ and $pk^{Z,l}_{A}$ respectively (where $Z_l$ is clear from context) - unless otherwise stated. 